I think it's entirely understandable why he would be angry. He's a participant in a music industry that has an agenda on what popular music is released and when, like a well-oiled machine. And while he may be bathing in money and Kim Kardashian's you-know-what, as an artist who is incredibly successful, he not only has to deal with the successes that such a position entails, but also the unending criticism, paparazzi, expectations, and industry coercion that could drive any person mad.
I find it good that he's channeling this "celeb/artist anger" in making angry music as opposed to becoming a drug addict like so many other artists who have crumbled under the weight of artistic value vs. industry-manufactured commercial appeal. And in hip-hop, where the industry is fueled by black men but run by white men, the idea of "new slaves" is nothing new, but nonetheless important and interesting. All because he has a lot of money doesn't mean the structure that gave him the money is not exploitative and wrongheaded.